This invention relates to an improved concentration process utilizing multistage, multiple effect evaporation systems.
Multistage evaporators are well known. As presently utilized, they require the circulation of large amounts of the liquid to be concentrated, and only the sensible heat of this liquid is converted to latent heat for evaporation. The separate stages are not provided with heating means, and it is not possible to create large differences in concentration of the circulating liquid as it passes from one stage to the next. Accordingly, the procedure is deficient in heat utilization and production efficiency.
Multiple effect evaporators are also well known. In these systems, the heat of the vapor generated in the one effect is utilized to evaporate liquid in a subsequent effect. The system is more efficient than the multistage system. However, conventionally, the effects have been linked in series with the result that the efficiencies of the systems are not satisfactory.
Other systems are known for the concentration of liquids by evaporation.
Many such systems are employed in large scale commercial production. They are, however, expensive and inefficient to operate since all require the generation and dissipation of heat energy. The art, therefore, is continuously engaged in efforts to improve the utilization of heat energy in liquid evaporation systems.